1. Field of the Invention
The present invention relates to a chess clock A chess clock which is used for registration of the total time each of two chess players is using for thinking over the moves, normally comprises two separate clock units which may alternately be started and stopped by means of a manually operatable change-over mechanism.
2. Description of Prior Art.
The known chess clocks generally consist of two separate mechanical clocks which by means of a rocking lever system influencing the function of the balance of each of these clocks, may be operated in such a manner that one of the clocks is started at the same time as the other clock is stopped, and vice versa. When one of the players (for example white) has made a move he stops his clock by depressing the rocking lever. Thereby the clock of the opponent (for example black) is simultaneously being started, and when the opponent has made a move he depresses the rocking lever and thereby stops his own clock and starts the other clock, etc. The known chess clocks are provided with a so-called "wing" which during the last minutes before the clock passes the hour is lifted up by the minute hand and then falls down again at the moment where the minute hand passes the hour. Chess is normally played according to rules prescribing that the players must have made a certain number of moves within a predetermined period of time, or that the total time of thinking over the moves may not exceed a certain maximum limit for the whole game. In order to utilize the signalling function obtainable by means of the said wing it is normal to preset the clock before the start of a game to such a time that the prescribed total maximum time for thinking over or the said predetermined period of time expires exactly by passing the hour. Thus, it is usual to preset the clock at 30 minutes in chess games where the rules prescribe that the first 40 moves must be made within 21/2 hours. In case of "blitz-game" where the total time of thinking over is normally only 5 minutes for each of the two players, the clocks are preset at 55 minutes so that the five minutes for the total game have expired when the wind falls by passing the hour. A few types of the mechanical chess clocks are also provided with a counter for registering the number of moves which have been made.
As mentioned above the known chess clocks have two totally separate, complete clock units and therefore it cannot be avoided that these units differ to a certain extent as far as accuracy is concerned, and this difference in accuracy may in some cases be decisive for the result of the game.